1. Field of the Invention
The present invention relates to a technology for confirming continuity between a network storage device and a host computer.
2. Description of the Related Art
This is a network storage device for providing volumes to a host computer via a network. The network storage device communicates with the host computer according to the network communication protocol used by the network to be connected. There are many types of networks, and the IP (Internet Protocol) network is one of them.
The protocol of the IP network has been standardized by the IETF (Internet Engineering Task Force), and protocols are hierarchical. For example, iSCSI (Small Computer Systems Interface protocol over the Internet) is a protocol for using the network storage device to be connected to the IP network, and is a host protocol which positions in the higher hierarchy of the IP.
In the IP network, Ping, which confirms continuity using the ICMP (Internet Control Message Protocol) standardized by the IETF, is widely known as a means for the host computer to confirm continuity with the network connection device. The host computer can confirm continuity with the device having a specified IP address in the IP layer, by using Ping (J. Postel, “RFC-792 Internet Control Message Protocol,” IETF, 1981).